Generally, electrophoretic display (EPD) has bistability and thus only consumes power at the moment of changing images. Thus, the EPD advantageously has lower power consumption. Such EPD utilizes the reflection technology, and the display effect and the image quality thereof are close to paper. Accordingly, the EPD is mostly applied in the electronic paper or electronic tags. FIG. 1 depicts an EPD, which includes a panel 10, a controller 12, a plurality of gate driver lines G1-G8, and a plurality of source driver lines S1-S8. There are several pixels 14 on the panel 10, and each pixel 14 is connected to one gate driver line and one source driver line. When the controller 12 receives a frame data, the controller 12 starts to drive the gate driver lines in orders of the location of the gate driver lines G1-G8, from the gate driver line G1 to the gate driver line G8 as shown in FIG. 2. In the meantime, the controller 12 determines the levels of a plurality of voltages which are applied to the source driver lines S1-S8 according to the frame data and the gate driver line that is driven. Referring to FIGS. 1 and 3, while driving the gate driver line G1, the controller 12 realizes that the pixels at (G1, S1), (G1, S5), (G1, S7) and (G1, S8) are set by black and the pixels at (G1, S2), (G1, S3), (G1, S4) and (G1, S6) are set by white according to the frame data. Thus, the controller 12 will apply a low level voltage to the source driver lines S1, S5, S7 and S8 and apply a high level voltage to the source driver lines S2, S3, S4 and S6, respectively. While driving the gate driver line G2, the controller 12 realizes that the pixels at (G2, S2), (G2, S3) and (G2, S5) are set by black and the pixels at (G2, S1), (G2, S4), (G2, S6), (G2, S7) and (G2, S8) are set by white according to the frame data. Thus, the controller 12 will apply the low level voltage to the source driver lines S2, S3 and S5 and apply the high level voltage to the source driver lines S1, S4, S6, S7 and S8, respectively.
In the EPD, when the voltages on the source driver lines S1-S8 change, switching currents IS1-IS8 will be generated. For example, when the gate driver line G1 in FIG. 1 stops driving, the gate driver line G2 will be driven sequentially. Referring to FIG. 3, the voltage levels on the source driver lines S1, S2, S3, S7 and S8 change, and the switching currents IS1, IS2, IS3, IS7 and IS8 are generated as shown in FIG. 4. Herein, generating the switching currents IS1-IS8 brings about the power consumption. In fact, the electronic paper and the electronic tags are mostly developed portable. Thus, the technology of the EPD should consider saving power.
However, besides the EPD, other displays (for example, the liquid crystal display, LCD) that utilize the gate driver lines and the source driver lines to change the color or the gray scale of the pixels also adversely generate the switching currents in time of changing the color or the gray scale of the pixels. Accordingly, such technology still fails to avoid wasting power.
Therefore, it is desired a method for lowering the switching current in order to reduce the power consumption.